We observe the locomotion of tissue culture cells, studying their responses to grooved surfaces, collagen fibers, layers of elastic rubber, chemical gradients and other special environments. By obstructing the normal paths of outgrowing nerve fibers (within developing chick and frog embryos) using thin filters of known permeability properties, we test whether these fibers are chemotaxis. By culturing fibroblasts on small spots of evaporated metals we try to determine exactly which properties of the substratum govern the phenomenon of anchorage dependence. By observing the adhesive contacts of normal and cancerously transformed cells using interference reflection microscopy and by pulling these same cells apart by micromanipulation, we attempt to determine how the adhesions of cancerous cells differ from those of normal cells. By comparing the amounts of distortion and wrinkling these cells produce in thin layers of silicone rubber, we look for proof that cancerous cells are characteristically less strongly contractile than their normal counterparts.